scholarly journals Effect of Host Plant Resistance and Reduced Rates and Frequencies of Fungicide Application to Control Potato Late Blight

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1113-1118 ◽  
Author(s):  
W. W. Kirk ◽  
K. J. Felcher ◽  
D. S. Douches ◽  
J. Coombs ◽  
J. M. Stein ◽  
...  
Keyword(s):  
Late Blight ◽  
Field Experiments ◽  
Potato Late Blight ◽  
Application Rate ◽  
Effective Control ◽  
Michigan State University ◽  
State University ◽  
Breeding Lines ◽  
Application Rates ◽  
Commercial Potato

Field experiments were conducted during 1998 to 2000 to determine the response of commercial potato cultivars and advanced breeding lines (ABL) differing in susceptibility to foliar late blight (caused by Phytophthora infestans) to reduced rates and frequencies of residual, contact fungicide applications. When environmental conditions were most favorable for the development of late blight, the lowest application rate of the fungicides chlorothalonil or fluazinam (33% of the manufacturers' recommended application rate [MRAR]) gave unsatisfactory control of potato late blight. Under conditions moderately conducive for late blight development, effective control was achieved with 33 to 66% MRAR with either fungicide. The Michigan State University advanced selection, MSG274-3, was the least susceptible ABL tested and, during 1998 to 2000, late blight was effectively managed using reduced rates of fungicides. Application rates of chlorothalonil (33 to 100% MRAR) significantly reduced late blight in the cultivar Snowden (5-day application interval) compared with the nontreated control; whereas, late blight was not effectively controlled in Snowden even at 100% MRAR of chlorothalonil at either 10- or 15-day application intervals in 1999 or 2000. The ABL MSG274-3 was the least susceptible of all cultivars and ABL used in this study, and required minimal chemical protection against late blight. The study demonstrates that ABL with reduced susceptibility to late blight can be managed with reduced fungicide rates and longer application intervals, thus offering more economical control of this disease.

scholarly journals Use of Phosphonate to Manage Foliar Potato Late Blight in Developing Countries

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1008-1015 ◽  
Author(s):  
Peter Kromann ◽  
Willmer G. Pérez ◽  
Arturo Taipe ◽  
Elmar Schulte-Geldermann ◽  
Buddhi Prakash Sharma ◽  
...  
Keyword(s):  
Developing Countries ◽  
Late Blight ◽  
Significant Relationship ◽  
Field Experiments ◽  
Meta Analysis ◽  
Potato Late Blight ◽  
Application Rate ◽  
Potato Foliage ◽  
Potato Genotype ◽  
The Cost

Twenty phosphonate products found in the agrochemical market in Ecuador and Peru were evaluated in bioassays for the control of foliar potato late blight, caused by Phytophthora infestans. Eight phosphonate products were evaluated in 16 field experiments done in Peru, Ecuador, Kenya, and Nepal. A meta-analysis across locations involving 71 combinations of potato genotype by site and year demonstrated a significant relationship between phosphonate application rate and efficacy for controlling late blight on potato foliage. The meta-analysis revealed that phosphonate rates of approximately 2.5 g a.i./liter provided efficacy similar to that of the conventional contact fungicides mancozeb and chlorothalonil used at similar rates. At rates higher than 2.5 g a.i./liter, the efficacy of phosphonate was superior to the contact fungicides. Overall, late blight control by phosphonate appeared relatively stable in field experiments across locations. An analysis of field experiments and 64 combinations of potato genotype by site and year showed no correlation between the susceptibility level of potato genotypes and efficacy of phosphonates. The cost of both phosphonate compounds and contact fungicides varied greatly among the countries of the field study; however, in Kenya, control with phosphonate was clearly less expensive than with mancozeb.

scholarly journals Ametoctradin: a new fungicide for potato late blight control

2016 ◽  
Vol 83 (0) ◽  
Author(s):  
Jesus Guerino Töfoli ◽  
Ricardo José Domingues ◽  
Walter Jacobelis Jr. ◽  
Marina Pacheco Lombardi Tortolo
Keyword(s):  
Late Blight ◽  
Block Design ◽  
Potato Late Blight ◽  
Significant Control ◽  
Progress Curve ◽  
Randomized Block Design ◽  
Commercial Potato ◽  
Crop Development ◽  
Potato Crops ◽  
Application Volume

ABSTRACT: Late blight (Phytophthora infestans ) is among the most important and destructive diseases in potato cultivation. Aiming to evaluate the efficacy of the new fungicide ametoctradin, mixed with dimethomorph and metiram, an experiment was carried out in commercial potato crops (Ágata cultivar) in Pilar do Sul, São Paulo state, Brazil, during the growing season in 2013. A randomized block design was used, with 4 replications, on plots of 15 m2. Applications were carried out using a backpack sprayer with a spray-bar under 3 bar of constant pressure. The application volume varied from 300 L to 600 L.ha-1 based on crop development. The variables evaluated were leaf severity (0 to 100%), area under the disease progress curve, and yield. Ametoctradin + dimethomorph (1.25 L.ha-1) provided significant control of late blight, exceeding benthiavalicarb + fluazinam, dimethomorph + metiram, dimethomorph + pyraclostrobin, cymoxanil + mancozeb, metalaxyl-M + mancozeb, ametoctradin + metiram, and pyraclostrobin + metiram, although similar to ametoctradin + dimethomorph (1.00 L.ha-1), fluopicolide + propamocarb, and fenamidone + propamocarb. Ametoctradin + metiram resulted in moderate control, which was always similar to the standard. Ametoctradin and its associations represent a new alternative for the management of potato late blight.

Influence of four commonly used pesticides on the survival, growth, and reproduction of the earthworm Aporrectodea trapezoides (Lumbricidae)

1998 ◽  
Vol 49 (8) ◽  
pp. 1297 ◽  
Author(s):  
L. P. D. Choo ◽  
G. H. Baker ◽  
L. P. D. Choo ◽  
G. H. Baker
Keyword(s):  
Filter Paper ◽  
Field Experiments ◽  
Application Rate ◽  
Normal Rate ◽  
Cocoon Production ◽  
Application Rates ◽  
Aporrectodea Trapezoides ◽  
Growth And Reproduction ◽  
Significant Mortality

The effects of 4 commonly used pesticides, endosulfan (insecticide), fenamiphos (nematicide), methiocarb (molluscicide), and ridomil (fungicide) on the survival, growth, and reproduction of the earthworm Aporrectodea trapezoides (Lumbricidae) were measured in laboratory and field experiments. When the earthworms were exposed to the pesticides on moist filter paper for 48 h, fenamiphos and, to a lesser extent, endosulfan caused significant mortality. In contrast, the survival of A. trapezoides was rarely affected by the pesticides during exposure for 5 weeks in pots and cages containing soil (only noted under 10 × normal application rate of endosulfan against adult worms). However, endosulfan did significantly reduce the weight of juvenile A. trapezoides within 5 weeks when applied to soil at normal application rate in both the field and laboratory. Fenamiphos did so at normal application rate in the field only. Fenamiphos and methiocarb reduced earthworm weight in the laboratory when applied at 10 × normal rate. The clitella of adult earthworms regressed with exposure to endosulfan at normal rate and also exposure to fenamiphos at 10 × normal rate. Cocoon production was inhibited by endosulfan and fenamiphos at normal application rates and methiocarb at 10 × normal rate. The use of some pesticides, in particular endosulfan, could significantly reduce the establishment of abundant and beneficial populations of earthworms in Australian pastures.

scholarly journals Effect of Gypsum Application Rate, Soil Type, and Soil Calcium on Yield, Grade and Seed Quality of Runner Type Peanut Cultivars

2017 ◽  
Vol 44 (1) ◽  
pp. 13-18 ◽  
Author(s):  
J.A. Arnold III ◽  
J.P. Beasley ◽  
G.H. Harris ◽  
T.L. Grey ◽  
M. Cabrera
Keyword(s):  
Field Experiments ◽  
Seed Quality ◽  
Soil Depth ◽  
Application Rate ◽  
Seed Vigor ◽  
Application Rates ◽  
Peanut Cultivars ◽  
Research And Education ◽  
The University ◽  
Gypsum Application

ABSTRACT Calcium (Ca) availability in the 0 to 8 cm soil depth often limits peanut yield and influences grade in the southeastern United States. Field experiments were conducted in 2012 and 2013 at the University of Georgia's Coastal Plain Experiment Station, Tifton, GA (CPES) and the Southwest Georgia Research and Education Center, Plains, GA (SWREC) to determine large-seeded (Georgia-06G) and medium-seed sized (Georgia Greener) runner-type cultivar response to gypsum application rates of 0, 560, 1120, 1650 kg/ha. Peanut pod yield and grade (TSMK) were significantly different between locations with 7610 and 6540 kg/ha at CPES and SWREC, respectively. However, there were no differences between peanut cultivars or gypsum rates. Standard germination, seed vigor (cold germination), and seed Ca content analysis were also conducted on subsamples from each plot. Average peanut seed germination was 97% across all samples. No differences were observed for standard germination or vigor testing. Differences in locations were observed for yield, TSMK, percent jumbo, percent medium kernels, and seed Ca content. Peanut cultivar and gypsum application rate had effects on seed Ca concentration. Seed Ca concentration levels were 825 and 787 mg/kg for Georgia Greener and Georgia-06G, respectively. Seed Ca content increased as field gypsum application rate increased at both locations.

scholarly journals The Effects of Host Diversity and Other Management Components on Epidemics of Potato Late Blight in the Humid Highland Tropics

2001 ◽  
Vol 91 (10) ◽  
pp. 993-1000 ◽  
Author(s):  
K. A. Garrett ◽  
R. J. Nelson ◽  
C. C. Mundt ◽  
G. Chacón ◽  
R. E. Jaramillo ◽  
...  
Keyword(s):  
Late Blight ◽  
Potato Production ◽  
Potato Late Blight ◽  
Planting Density ◽  
Susceptible Host ◽  
Host Diversity ◽  
Progress Curve ◽  
Commercial Potato ◽  
Diversity Effect ◽  
Diversity Effects

A field study at three highland sites near Quito, Ecuador, was conducted to determine whether host-diversity effects on potato late blight would be as important as recently found in studies conducted in temperate areas. We compared three potato mixtures and use of mixtures in combination with different planting densities and two fungicide regimes. Treatment comparisons were made by absolute and relative measures of host-diversity effects and incorporating a truncated area under the disease progress curve as a means of standardizing comparisons across sites. Potato-faba intercrops consisting of only 10% potato provided an estimate of the effects of dilution of susceptible host tissue. Host-diversity effects were very different across study sites, with a large host-diversity effect for reduced disease only at the site most distant from commercial potato production. Planting density had little influence on host-diversity effects or on late blight in single-genotype stands. Fungicide use in combination with potato mixtures enhanced a host-diversity effect for reduced late blight. Potato-faba intercrops produced only a small decrease in potato late blight. Effects of host diversity on yield were variable, with the greatest increase in yield for mixtures treated with fungicides at the site most distant from commercial potato production. The effects of host diversity on late blight severity may be less consistent in the tropical highlands than in the temperate zone, but can contribute to integrated disease management.

scholarly journals Field Evaluation of Reduced Rate Brassicaceae Seed Meal Amendment and Rootstock Genotype on the Microbiome and Control of Apple Replant Disease

2019 ◽  
Vol 109 (8) ◽  
pp. 1378-1391 ◽  
Author(s):  
Likun Wang ◽  
Mark Mazzola
Keyword(s):  
Disease Control ◽  
Growing Season ◽  
Application Rate ◽  
Soil Fumigation ◽  
Seed Meal ◽  
Effective Control ◽  
Apple Replant Disease ◽  
Replant Disease ◽  
Application Rates ◽  
Reduced Rate

An orchard field trial was conducted to assess the utility of reduced rate Brassicaceae seed meal (SM) amendment in concert with specific rootstock genotypes for effective control of apple replant disease. Three amendment rates of a 1:1 formulation of Brassica juncea-Sinapis alba SM were compared with preplant 1,3-dichloropropene/chloropicrin soil fumigation for disease control efficacy. When applied at the highest rate (6.6 t ha−1) in the spring of planting, SM caused significant phytotoxicity and tree mortality, which was higher for Gala/M.26 than for Gala/G.41 but was not observed at SM application rates of 2.2 or 4.4 t ha−1. SM treatment resulted in growth and yield increases of Gala/M.26 and Gala/G.41 trees in a manner similar to the fumigation treatment and significantly greater than the no treatment control. Tree growth in soils treated with SM at 4.4 t ha−1 was similar or superior to that obtained with SM at 6.6 t ha−1 and superior to that attained at an SM application rate of 2.2 t ha−1. Soil fumigation and all SM treatments reduced Pratylenchus penetrans root infestation relative to the control treatment at the end of the initial growing season. Lesion nematode root densities in the fumigation treatment, but not SM treatments, rapidly recovered and were indistinguishable from the control at the end of the second growing season. Soil fumigation and all SM treatments significantly suppressed Pythium spp. root infection relative to the control. Trees grafted to rootstock G.41 possessed lower P. penetrans root densities relative to trees grafted to rootstock M.26. One year after planting, composition of microbial communities from SM-amended soils was distinct from those detected in control and fumigated soils, and the differences were amplified with increasing SM application rate. Specific fungal and bacterial phyla associated with suppression of plant pathogens were more abundant in SM-treated soil relative to the control, and they were similar in abundance in 4.4- and 6.6-t ha−1 SM treatments. Findings from this study demonstrated that use of the appropriate apple rootstock genotype will allow for effective replant disease control at SM application rates significantly less than that utilized previously (6.6 t ha−1).

scholarly journals Yield and resistance of potato cultivars with colour flesh to potato late blight

2017 ◽  
Vol 63 (No. 7) ◽  
pp. 328-333
Author(s):  
Pazderů Kateřina ◽  
Hamouz Karel
Keyword(s):  
Late Blight ◽  
Field Experiments ◽  
Potato Late Blight ◽  
Russet Burbank ◽  
Weak Dependence ◽  
Potato Cultivars ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Better Than

The resistance to potato late blight (as AUDPC – the area under the disease progress curve) and yield were evaluated in precise field experiments with 13 colour-fleshed potato cultivars. Red Emmalie and Blaue Anneliese were the most profitable cultivars of potatoes with coloured flesh, the overall yield did not differ statistically from the control cv. Agria. Cv. Blaue Anneliese resistance to potato late blight was considerably better than both control cultivars, other 2 cultivars HB Red and Red Emmalie were similar to cv. Agria. Surprisingly, cv. Russet Burbank was found to be more resistant than most cultivars tested. A statistically significant weak dependence (r = 0.36) between the percentage of infestation of plants in the T6 evaluation date (6–8 August in individual years) and the yield was detected, the slightly stronger (r = 0.40) was the correlation between AUDPC values and total yields.

Indaziflam Enhances Buckhorn Plantain (Plantago lanceolata) Control from Postemergence Herbicides

2015 ◽  
Vol 29 (1) ◽  
pp. 147-153 ◽  
Author(s):  
Patrick E. McCullough ◽  
Christopher R. Johnston ◽  
Thomas V. Reed ◽  
Jialin Yu
Keyword(s):  
Field Experiments ◽  
Plantago Lanceolata ◽  
Application Rate ◽  
Poor Control ◽  
Perennial Weed ◽  
Application Rates ◽  
Shoot Mass ◽  
Annual Weeds ◽  
Postemergence Herbicides ◽  
Biomass Reduction

Buckhorn plantain is a perennial weed in turfgrass and efficacy of POST herbicides is often inconsistent for control in spring. Indaziflam is a cellulose biosynthesis inhibitor used for PRE control of annual weeds in turf and applications have shown to be injurious to established buckhorn plantain. The objectives of this research were to evaluate (1) effects of indaziflam application rate and placement on buckhorn plantain injury; (2) effects of tank-mixing indaziflam with POST herbicides for buckhorn plantain control; and (3) physiological effects of indaziflam on absorption and translocation of14C-2,4-D in buckhorn plantain. In greenhouse experiments, indaziflam reduced buckhorn plantain shoot mass 61 to 75% from the nontreated at 4 wk after treatment (WAT) and hierarchical rank of application placements were: foliar + soil ≥ soil ≥ foliar. Differences in biomass reduction from application rates (27.5 and 55 g ai ha−1) were not detected. In field experiments, indaziflam at 55 g ha−1controlled buckhorn plantain 34% at 9 WAT but enhanced the speed of control from all herbicides tested in tank mixtures. Exclusive applications of 2,4-D or 2,4-D + dicamba + MCPP provided poor control (< 70%) of buckhorn plantain at 9 WAT, but tank mixtures with indaziflam provided 81 and 98% control, respectively. Fluroxypyr and simazine alone controlled buckhorn plantain < 38% but tank mixtures with indaziflam enhanced control more than twice as much from exclusive applications. Tank-mixing indaziflam with metsulfuron did not improve control from metsulfuron alone after 9 wk. Bermudagrass injury was not detected from any treatment. In laboratory experiments,14C-2,4-D absorption and translocation in buckhorn plantain was similar with or without indaziflam tank mixtures at 72 and 168 h after treatment. Overall, indaziflam may improve buckhorn plantain control from POST herbicides by providing additive phytotoxicity in tank mixtures in spring.

The effect of application rate of chemical herbicides on weed control and yield in early potatoes

1971 ◽  
Vol 77 (2) ◽  
pp. 243-246
Author(s):  
Maurice Eddowes
Keyword(s):  
Weed Control ◽  
Field Experiments ◽  
Sandy Loam ◽  
Low Cost ◽  
Application Rate ◽  
Control Treatment ◽  
Application Rates ◽  
Herbicide Mixtures ◽  
Rate Controlled ◽  
Annual Weeds

SummaryIn a series of field experiments from 1966 to 1969, on light sandy loam soils in the West Midlands, comparisons were made between two levels of application of herbicides based on urea, triazine and bipyridil compounds for weed control in early potatoes.Under conditions of adequate nutrient and water supply, the high application rate controlled about 94%, and the low application rate about 88% of the annual weeds. At equivalent application rates, urea compounds and herbicide mixtures containing ureas, gave superior weed control to triazine compounds and herbicide mixtures containing triazines, but the ureas were apparently more phytotoxic to the potatoes.In 1970, comparisons were made between three levels of application of ametryne and monolinuron, high, medium and low and an unsprayed control treatment.The highest yields of potatoes were associated with the low application rates of herbicides from 1966 to 1970.It was concluded that, on these light sandy loam soils, when irrigation is available, relatively low application rates of either monolinuron or ametryne, or mixtures of ureas or of triazines, or mixtures of bipyridils and ureas or triazines could give adequate control of annual weeds in early potatoes at low cost.

scholarly journals Selection Progress for Resistance to Iris Yellow Spot in Onions

HortScience ◽  
2018 ◽  
Vol 53 (8) ◽  
pp. 1088-1094 ◽  
Author(s):  
Neel Kamal ◽  
Christopher S. Cramer
Keyword(s):  
Disease Severity ◽  
First Generation ◽  
Disease Incidence ◽  
Thrips Tabaci ◽  
Yellow Spot ◽  
Effective Control ◽  
State University ◽  
Onion Thrips ◽  
Breeding Lines ◽  
New Mexico State University

Onion thrips (Thrips tabaci Lindeman)–vectored Iris yellow spot virus (IYSV) causes the disease Iris yellow spot (IYS), which is a major threat to the sustainability of onion production worldwide. An increase in thrips resistance to various insecticides, high costs, and the limited efficacy of insecticides under hot and drier conditions found in various onion-growing regions restrict grower’s options for effective control of thrips and spread of IYSV. Because cultivars resistant to thrips and IYS are lacking, this study was undertaken to measure selection progress for IYS resistance after one selection cycle. In 2009, selections were performed on previously evaluated New Mexico State University (NMSU) breeding lines that showed some reduced IYS disease symptoms, and the selected plants self-pollinated the following year. In 2011 and 2012, plants from the original and selected populations along with a susceptible check, ‘Rumba’, were evaluated under field conditions when onion thrips and IYSV were present. Plants were rated for IYS disease severity and the number of thrips per plant was recorded three times during the study in each year. First-generation material, NMSU 10-776, NMSU 10-782, NMSU 10-785, NMSU 10-807, and NMSU 10-813, had fewer thrips number per plant, lower disease severity, and disease incidence than their original breeding lines on at least one or two rating times in both years. Some first-generation breeding lines performed better with a lower thrips number and disease severity than their original population in 1 year or the other. Most entries exhibited fewer thrips, lower IYS disease severity, and less incidence than the susceptible check ‘Rumba’ at most rating times. Overall, some progress was observed in this first-generation material for reduced IYS disease symptom expression when compared with their original populations.

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